Gyro slip ring structure



Oc. E6, 1956 H. G. swANsoN 2,756,625

GYRO SLIP RING STRUCTURE Filed Dec. 31, 1952 2 Sheets-Sheet 1 Inventor: Harry G. Swanson b5 @Ma/@6.

His Attovneg.

@et R6. i956 H. G. swANsoN GYRO` SLIP RING `STRUCTURE;

2 Sheets-Sheet 2 Filed Dec. 3l, 1952 Ihvetor: Haw-"5 G. Swanson.'

b5 His Attorheg.

GYRO SLIP RING STRUCTURE Harry G. Swanson, Lynn, Mass., assigner to General Electric Company, a corporation of New York Application December 31, 1952, Serial No. 329,075

11 Claims. (Cl. 74-5) The present invention relates to electrical connection lapparatus and, more particularly, to improved arrangements for accomplishing low-friction electrical couplings between relatively rotatable gyroscope members.

Gyroscopic instruments commonly include gimballed members which have complete rotational freedom about one or more of the instrument axes and, further, are associated with electrical apparatus which requires that electrical connections be maintained between leads on different ones of the relatively rotatable parts. The number of such connections which must be brought along the major axis of a conventional three-axis gyro may be sizeable, particularly when the rotor is electrically driven and electrical devices such as pick-offs and torque motors are utilized. It is essential, however, that the frictions experienced about any gyroscope support axis be kept at an -absolute minimum, else the resultant precession destroys instrument accuracy, so that, even with low-friction bearings, precision operation of la gyroscope may be realized only if the electrical connection apparatus is also substantially frictionless. In those applications where less than 360 degrees of freedom between rotatable parts is required, the desired connections may be established through fine conducting spirals. Elsewhere, particularly about the major axes of three-'axis gyroscopes, full rotational freedom between parts bars the use of spirals and necessitates connection through slip rings and brushes.

Slip ring structures may afford satisfactory low-friction coupling when properly adjusted to have optimum brush contact pressures and when the sliding contacts between rings and brushes are not established at such large radial distances from the axis of rotation that the resulting torques are large. Practically, these conditions are difficult to realize, because arrangements for adjusting delicate brushes may occupy considerable space and because small diameter slip rings and minute brushes cooperating with them are not easily or quickly assembled and disassembled.

In accordance with the present teachings, these difficulties are avoided in a ring `and brush assembly wherein flexible conducting brushes are supported in a rotatably adjustable holder which is mounted eccentrically in relation to the axis of the slip rings. Angular movement of the holder causes the brushes to move between positions of variable pressure engagement with the rings and a position wherein the brushes are entirely free of the rings and their insulating separators. The unitary brush and holder assembly may be moved axially in relation to the slip rings, thereby enabling a rapid assembly or disassembly of the connection apparatus, and unit construction of the brush and holder assembly is not only structurally simple but is conveniently realized in a very small size.

It is therefore one object of the present invention to provide improved apparatus for maintaining electrical circuit connections between relatively rotatable members.

Another object is to provide a Icompact low-friction slip ring land brush arrangement for gyroscopes.

Further, it is an object to provide a substantially frictionless gyro slip ring and brush arrangement which may be simply assembled and accurately adjusted.

By way of a summary -account of one aspect of this invention, there are provided a plurality of small-diameter conducting slip rings axially spaced along the axis of relative rotation between two gyro members, the rings being insulated from one another, electrically connected with lead wires passing through the rings, and supported for rotation with one of the two gyro members. The brushes comprise line .conducting wires or strips of a generally spiral shape, the outer ends of the brushes being supported in a hollow cylindrical holder such that the plane of each is normal to the axis of the holder and such that they are axially spaced in accordance with the spacings of the slip rings which they contact. Insulation separates the individual brushes, and each brush is connected with an electrical lead wire. The unit formed by the holder and the brushes, leads, and insulation within it is supported by the other of the gyro members, but the longitudinal axis of the holder unit is eccentrically positioned in relation to the axis of rotation of the two gyro members, which latter axis is also that of the slip rings. Further, the holder is supported for independent and adjustable angular movement about its own longitudinal axis, in addition to being movable in an axial direction to permit disassembly and re-assembly of the connection apparatus. Because of the eccentric relationship between the central axes of the slip rings and brushes, angular movement of the brush holder is effective to vary the pressures of contact between the brushes and rings or to separate the rings and brushes sufficiently to permit the brush holder unit to be withdrawn axially.

Although the features of this invention which are believed to be novel are set forth in the appended claims,

' greater detail of the invention itself and further objects and advantages thereof may be readily comprehended by reference to the following description taken in connection with the accompanying drawings, wherein:

Figure l is a longitudinal cross-sectional view of an electrical connection apparatus taught by this invention;

Figure 2 is a cross-section of the connection apparatus of Figure l viewed upon the surface defined by line 2 2 in Figure l;

Figure 3 comprises a cross-sectional view similar to that of Figure 2, with illustrations of relative brush and ring positions for several angular orientations of the brush holder;

Figure 4 represents a gyro slip ring land brush assembly about the major axis of a three-axis gyroscope; `and Figure 5 is a cross-section of the gyro connection assembly Viewed upon the surfaces defined by line 5 5 in Figure 4.

In a preferred embodiment of the pre-sent invention appearing in Figures l and 2, the members 1 and 3 are relatively rotatable about an axis 4 4, the threaded cylindrical insert 6 in member 1 having an end 7 which has a cylindrical bore concentric with axis 4-4 to receive the outer raceway 8 of a ball bearing unit 9. The other of the relatively rotatable members 3 has a cylindrical shaft or trunnion portion 10 which supports inner raceway 1l, the bearing balls 12 being positioned between the raceways to complete the low-friction bearing structure intermediate members 1 and 3. Shaft portion 10 supports a hollow shaft 13 which is constructed of insulating material and extends along axis 1 -4; and circular conductors or slip rings 14 are spaced along shaft 13 concentric therewith and separated by insulatingspacers 15 which preferably have a larger diameter than the slip rings. Electrical leads 16 are connected with slip rings 14, either through soldering or pressure contact between the rings and lead ends, and pass through 3 the 'hollow interior of shafts 1li and 13 to the circuit components with which they are associated.

The seven brushes or contact members 17 are formed of flat ilexible conducting material and the innermost wiping end portion 1S of each brush is rolled cylindrical for low-friction contact with the periphery of a slip ring. From the wiping ends, the brushes extend outwardly with a somewhat spiral curvature, which advantageously enhances the brush resiliency, and the outer end portions are curved in circular arcs to facilitate the supporting of these outer ends within the metal support rings 19 to which they are attached, as by soldering. Electrical leads 20 are soldered near the outer ends of brushes 17 and are connected in appropriate circuits. The combination of a spiral brush, its support ring, and connecting lead, may be assembled as a single unit. These units are stacked alternately with insulating spacers and supports 21 within a substantially cylindrical metal holder 22 which has its ends turned inwardly to hold the spacers and brush units fixedly in position. Spacers 21 have only relatively small circular openings therethrough, just providing clearance for the slip ring spacers 15, whereby the individual brushes cannot be vibrated out of positional correspondence with the slip rings they should contact. Accidental shorting of a brush with other slip rings is thus precluded. Arcuate openings 23 in the spacers 21, all of which openings are in line, form a passageway for the electrical leads 29 to be brought through the stack and to be confined to positions Where they cannot interfere with proper operation of the brushes and slip rings.

Holder 22 and the brushes, spacers and leads associated with it comprise a self-sustaining unit or cartridge which may be conveniently constructed to be extremely compact and to have a structural soundness and simplicity. it is a distinct advantage that the cartridge or holder unit may be easily mated with and withdrawn from its cylindrical'recess 24, in the insert 6 of member 1, thereby facilitating not only the original assembly but also any subsequent operations disturbing the connection apparatus. Gne means which has been employed to maintain the holder 22 in a fully seated relationship in recess 24, and also to restrict angular movement of the holder, is illustrated as comprising one or more locking brackets, such as 25, which are each held on the insert 6 by a screw 26, and extend downwardly into the recess where one surface abuts an end of the holder and where a bracket projection 27 meshes with a slot in the holder to preclude angular displacement of the holder. It should be apparent that the desired locking may be achieved in other ways.

The common longitudinal axis of recess 24 and brush holder 22 is displaced from and parallel to the axis 4 4, which is the axis of the slip rings 14 and the axis of relative rotation between members 1 and 3. By virtue of this eccentric relationship, simple angular movement of holder 22 enables adjustment of brush pressure upon slip rings 14 and also enables the brush ends 18 to be displaced from rings 14 and spacers 15 by a suflicient distance to permit the brush holder to be moved into or ont of recess 24 without damage to the brushes and without necessitating laborious and inconvenient lifting of the brushes. Angular motion of the holder may be produced by a suitable tool in engagement with the slots at the outer end of the holder, or in any other convenient manner, the bracket 25 being removed to permit. such movement.

Referring to Figure 3, the brush .t7 is illustrated out of engagement with its corresponding slip ring 14, a condition which obtains when holder 22 is angularly oriented to cause the wiping end 13 of brush 17 to be suspended beyond the reach of the periphery of slip ring 14. The center of `the holder unit 2S, is out of coincidence with slip ring axis 4 4, such that the holder is eccentrically positioned in relation to that axis. As a consequence of this eccentric relationship, counterclockwise movement of brush 17, which results from counterclockwise rotary motion of holder 22 about center 28, causes the brush to be brought nearer the slip ring. Two additional angular positions of brush 17 are illustrated in Figure 3 to show the brush and ring contact which may be realized, brush position 17 depicting the brush and ring relationships for a counter-clockwise movement of about 45 degrees, and brush position 17 representing the full contact relationships for about a degree countcrclociiwise displacement. When the connection structure is being assembled, holder 22 is oriented to position brushes 17 such that there will be a separation between the brushes and the slip rings and spacers as the holder is inserted into the recess 24. Thereafter, with the holder seated in insert 6, a simple counterclockwise motion of the holder results in engagement between the brushes and the slip rings, the pressure of contact being adjustable with slight angular movement of the holder in appropriate directions. Locking bracket 25 preserves the desired relationships. Removal of the holder cartridge is readily accomplished by moving it clockwise and withdrawing it from recess 24, the need for lifting of brushes away from the slip ring insulators being obviated by the separation of brushes and slip ring assembly which occurs upon clockwise movement of they brush holder.

The extremely low frictions, ease of adjustment, economy of size, and other advantages which characterize the subject connection apparatus are particularly important in electrical couplings for gyroscopic instruments. Accordingly, one embodiment of this invention which ernbraces gyroscope structure is illustrated in Figures 4 and 5, the latter being a partial view of the instrument showing a cross-section of the connection apparatus surfaces as exposed along the section line 5-5 in Figure 4. The instrument includes a gyro rotor 29 supported in rotor gimbal 3i) for rotation about its spin axis 31, andthe gimbal 30 is pivotally supported in the main gimbal 32 by minor axis trunnions 33, which are perpendicular to the spin axis. Major axis 34--34 is perpendicular to the minor axis of trunnions 33 and is the axis about which relative movement between the main gimbal 32 and the outer frame or support member 35 is permitted to occur. As is well known, the outer frame of a gyroscope is normally supported by a craft such that the relative displacements of the rotor and main gimbals and of the main gimbal and outer frame are representative of craft attitudes in relation to the fixed spin axis attitude preserved bythe gyroscopic inertia of the rapidly spinning gyro rotor. Complete rotational freedom about the major axis is usually required, and it is about this axis that electrical connections must be brought to such electrical equipment as a motor kdriving the gyro rotor, a pick-olf detecting relative displacements between the main and rotor gimbals, a torque motor operating to exert torques between the main and rotor gimbals, and gravitationally-responsive tilt detectors mounted on the rotor and main gimbals. Equipment of this type, and appropriate use and connection thereof, though not illustrated, are wellknown to those versed in the art. The multiple electrical connections about the major axis 34-34 occasioned by the use of such equipment are aiorded by the connection apparatus 36 which includes slip rings 37 movable with the main gimbal 32 and brushes 38 supported with the outer frame 35. The cup-shaped member 39 which is threaded into outer frame 35 and locked therewith by locking nut 40 is provided with a recess 41 for the brush holder assembly and also serves as the support for an outer lraceway of a major axis bearing 42 which cooperates with a major axis trunnion 43 of main gimba-l 32. Slip rings 37 are mounted upon a hollow insulating shaft 44 which is co-extensive with part of the major trunnion axis 34-34, and the brushes 3S are stacked in acye lindrical brush holder 45 which is .inserted into the recess 41 and which has a longitudinal axis displaced from and parallel to the major trunnion axis. Individual brushes are axed to support rings 46 and connected with electrical leads 47, the brush and ring units thus formed being spaced and supported in insulating spacers 48 within the holder 4S. The holder cartridge is locked into the desired position by means such as lock nut 49, which is threaded onto an end of the cup-shaped member 39. Electrical leads, such as 50, couple slip rings 37 with the gyro electrical equipment. A fine adjustment of brush contact pressures which produces a satisfactory compromise etween good electrical contact of slip rings and brushes and minimized friction may be made accurately and readily through the simple expedients of moving holder 45 angularly until the desired engagement obtains and then fastening lock nut 49. The fit between holder 45 and the member 39 is selected such that the brush holder may be angularly oriented with ease, either manually or by a suitable tool in engagement with holder end slots 51 The slip rings employed in the electrical connection apparatus of the present invention may comprise conductors of any convenient construction which affords the circular peripheral contact surfaces; for example, slip ring units of very small size may have contact surfaces plated or otherwise deposited on an insulating slip ring shaft. Brushes having constructions other than those illustrated may also be utilized, preferably having some means for resiliently urging the wiping potrions of the brushes into contact with the slip ring surfaces. The resilient biasing and support of the brushes is preferably such that each brush is urged radially inward in the brush holder to a position nearer the axis of relative rotation between the coupled members than the periphery of its slip ring, for one angular position of the brush holder, and is urged inward to a position further from the axis of relative rotation than the outermost portion of the slip ring assembly when the brush holder is in another angular position. Such support of the brushes permits variable pressure contact between brushes and rings to be obtained and also enables the brush holder to be withdrawn from the apparatus without interference between the brushes and the slip ring assembly.

It should be apparent that the specific embodiments of this invention shown and described herein are of a descriptive rather than a limiting nature, and that various changes, combinations, substitutions or modifications may be employed by those skilled in the art in accordance with these teachings and without departing in spirit or scope from this invention in its broader aspects.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Electrical connection apparatus for members relatively rotatable about one axis, comprising at least one arcuate electrical conductor mounted in a fixed relationship with one of said members for movement therewith about said one axis, adjustable support means on another of said members movable in a circular path encompassing said one conductor, said circular path having a central axis displaced from and parallel to said one axis, at least one conducting contact element attached to said support means and disposed inwardly of said circular path in a position to engage and disengage said one conductor upon movement of said support means about said central axis whereby angular movement is effective to cause disengagement and engagement between said contact element and conductor.

2. Electrical connection apparatus comprising at least one conducting ring mounted in a fixed relationship with one of a pair of relatively rotatable members and concentric with the axis of relative rotation between said members, adjustable support means on the other of said members movable in a circular path encompassing said conducting ring, said circular path having a central axis displaced from and parallel to said axis of relative rotation,

at least one conducting brush resiliently attached to said support means and disposed inwardly of said circular path in a position to engage and disengage said conducting ring upon movement of said support means about said central axis, whereby angular movement of said means is effective to cause disengagement and variable pressure engagement between said brush. and ring.

3. Electrical connection apparatus for a pair of members relatively rotatable about one axis, comprising slip rings mounted concentric with said axis on one of said members, resiliently mounted brushes for contacting said slip rings, and angularly adjustable means supporting said brushes on the other of said members for adjustable angular movement around said slip rings about an axis displaced from and parallel to said one axis whereby angular movement of said adjustable means is effective to cause disengagement and variable pressure engagement between said brushes and slip rings.

4. Electrical connection apparatus for a pair of members relatively rotatable about one axis, slip rings insulated from one another and mounted on one of said members concentric with and axially spaced along said one axis, conducting brushes, one for contacting each of said slip rings, and angularly adjustable brush holding means resiliently mounting said brushes on the other of said members to contact the peripheries of said rings, said holding means encircling said slip rings and being rotatable about an axis displaced from and parallel to said one axis.

5. Electrical connection apparatus for a pair of members relatively rotatable about one axis, comprising a slip ring unit mounted on one of said members and having a plurality of conducting slip ring surfaces concentric with and distributed axially along said one axis; a cylindrical brush holder unit, said holder unit comprising a plurality of conducting brushes, and means supporting said brushes in a spaced relationship for contact with said slip ring surfaces; and means supporting said brushholder unit on the other of said members about said slip ring unit in position to permit engagement between said brushes and slip ring surfaces, said brush holder supporting means being angularly adjustable about an axis parallel to said one axis, whereby angular movement of said holder is effective to cause disengagement and variable pressure engagement between said brushes and slip ring surfaces.

6. Electrical connection apparatus for a pair of members relatively rotatable about one axis, comprising a slip ring unit on one of said members having a plurality of insulated slip ring surfaces concentric with and distributed axially along said one axis; a brush holder unit, said holder unit comprising a plurality of resilient brush means, and means supporting said brush means in a spaced and insulated relationship to permit contact with said slip ring surfaces; and means supporting said brush holder unit on the other of said members for adjustable angular movement in an arcuate path encircling said slipring unit about an axis parallel to said one axis to effect variable pressure engagement between said brush means and slip ring surfaces.

7. Electrical connection apparatus for gyroscope trunnion and support members relatively rotatable about a gyroscope support axis, comprising a plurality of circular conductors supported by said trunnion member concentric with said gyroscope axis, a plurality of resilient contact members, and substantially cylindrical holder means carried by said support member mounting said contact members to contact the peripheries of said circular conductors, said holder means encircling said circular conductors and being adjustable to position said contact members angularly about an axis eccentric in relation to said gyroscope axis to effect disengagement and variable pressure engagement between said contact members and conductors.

8. Electrical connection apparatus for gyroscope trunnion and support members relatively rotatable about a gyroscope support axis, comprising slip ring conductors supported by said trunnion concentric with said gyroscope axis, a plurality of flexible conducting brushes, a brush holder mounted on said support member around said slip rings for adjustable angular movement about an axis parallel to said gyroscope axis, and means supporting said brushes in said holder in a substantially normal relation to said parallel axis whereby angular movement of said holder is effective to `cause disengagement and variable pressure engagement between said brushes and slip ring conductors.

9. Electrical connection apparatus for gyroscope trunnion and support members relatively rotatable about a gyroscope support axis comprising a substantially cylindrical brush holder, a plurality of resilient conducting brush members, means supporting said brush members in said holder in an insulated and axiallgespaced relationship, said brush holder being supported in said support member for adjustable angular movement about its longitudinal axis and with said longitudinal axis eccentric in relation to said gyroscope axis, and a plurality of slip rings supported by said trunnion member in an axiallyspaced and insulated relationship and concentric with said gyroscope axis, said slip rings being disposed within said holder for contact with said brush members.

10. Electrical connection apparatus as set forth in claim 9 wherein each of said brush members comprises a exible wire brush having a substantially spiral curvature intermediate a substantially circular outer support portion and an inner wiping portion, and wherein said brush member supporting means comprises substantially annular insulators, said brushes and insulators being stacked alternately within said brush holder.

11. Electrical connection apparatus cooperating with a gyroscope outer frame member and a hollow main gimbal trunnion relatively rotatable about the major gyroscope axis, said outer frame member having an opening therethrough formed by a cylindrical bearing bore concentric with said major axis and a substantially cylindrical brush holder recess having an axis eccentric in relation with said 4major axis, comprising bearing means in said bearing bore supporting said trunnion about said major axis, a hollow insulator supported with said trunnion about said major axis and disposed in said brush holder recess, a plurality of conducting slip rings mounted in an axially-spaced relationship on said insulator, electrical leads coupled with said slip rings and passing through said hollow insulator and trunnion, a substantially cylindrical brush holder supported by said frame member in said brush holder recess for adjustable angular movement about said brush holder recess for adjustable angular movement about said eccentric axis, a plurality of substantially annular insulating brush separators, a plurality of thin wire brushes each having a substantially spiral curvature outwardly from an inner wiping portion, circular support rings each supporting one of said brushes in a substantially coplanar relationship, said separators and brush and ring units being alternately stacked in said brush holder such that said brushes are disposed to contact said slip rings.

References Cited in the tile of this patent Y UNITED STATES PATENTS 1,192,468 Shonnard July 25, 1916 1,612,405 Weaver Dec. 28, 1926 2,198,023 Bode et al Apr. 23, 1940 2,523,081 Wendt Sept. 19, 1950 2,595,951 Konet et al May 6, 1952 

